- Eating oatmeal may help lower cholesterol in people with metabolic syndrome.
- The study suggests that your gut microbiome may help create the benefit.
- Adding oatmeal to your diet can be a practical strategy to support heart health.
If your doctor has mentioned that your cholesterol numbers could use some work, you’re not alone. Nearly 10% U.S. adults have total cholesterol levels above the recommended range, and many are looking for dietary changes that can make a real difference. You have likely heard that oatmeal is good for your heart, but new research suggests its benefits go beyond what we previously understood—and your gut bacteria may deserve some of the credit.
A new study published in Nature Communications found that eating oatmeal can significantly reduce LDL (“bad”) cholesterol levels in as little as two days, with reductions of about 10% in people with metabolic syndrome. Even more surprising, the researchers discovered that much of this benefit comes from compounds produced when your gut microbiome breaks down the oats you eat.
If you have been wondering whether adding more oatmeal to your routine is worth it—or how much you would need to eat to see results—this study offers some compelling answers. Here’s what the researchers found and how you can put it into practice.
How Was This Study Conducted?
Researchers from the University of Bonn in Germany conducted two randomized controlled dietary interventions involving a total of 68 adults with metabolic syndrome—a cluster of conditions that includes central obesity, high blood pressure, elevated blood sugar and abnormal cholesterol levels. All participants were between 45 and 70 years old.
In the first study, 32 participants were randomly assigned to either a short-term, high-dose oat diet or a control diet for two days. Those in the oat group ate three oat meals daily, each containing about 100 grams (roughly 1 cup) of rolled oat flakes—totaling 300 grams per day. The control group ate macronutrient-matched meals without oats. The oat group was followed for six additional weeks as they returned to their normal diet.
In the second study, 34 participants were assigned to either replace one meal daily with an oat meal (80 grams of oat flakes) or continue their usual Western diet for six weeks. The researchers collected blood and stool samples to analyze cholesterol levels, gut bacteria composition and metabolomic profiles—essentially measuring what metabolites were circulating in participants’ bodies.
What Did the Study Find?
The results were particularly striking for the short-term, high-dose oat diet. After just two days, participants in the oat group experienced significant reductions in both LDL (“bad”) cholesterol (about 10%) and total cholesterol (about 8%) compared to the control group. Perhaps even more interesting, cholesterol levels tended to stay below baseline during the six-week follow-up period, even after participants returned to their regular diets.
Both oat interventions led to increased levels of ferulic acid, a phenolic compound found in oats, in participants’ blood. The high-dose oat diet also increased dihydroferulic acid, a metabolite produced when gut bacteria break down ferulic acid. This is significant because the researchers found strong associations between these microbially produced phenolic compounds and the reduction in cholesterol levels.
The six-week moderate oat diet showed milder effects. While it increased some phenolic metabolites and appeared to stabilize cholesterol levels, it did not produce the same dramatic cholesterol reductions as the short-term, high-dose approach. The researchers suggest this may be because individual differences in gut bacteria composition and dietary habits play a larger role when oat consumption is more moderate.
It’s worth noting that this study had a relatively small sample size, which means the results should be confirmed in larger studies. The participants were primarily Caucasian adults from Germany, so the findings may not apply to all populations. Additionally, some dietary information was self-reported, which always leaves room for error.
How Does This Apply to Real Life?
If you are looking to support your heart health, these findings suggest that oatmeal may be an even more powerful tool than we realized—particularly when consumed in larger amounts. While eating 300 grams of oat flakes daily (the amount used in the high-dose study) is not practical for most people long term, the study suggests that periodic oat-focused days could be a useful strategy for people looking to improve their cholesterol levels.
Here are some practical ways to incorporate more oats into your routine:
- Start your day with oatmeal. A bowl of oatmeal for breakfast is one of the easiest ways to increase your oat intake. Try topping it with berries, nuts or a drizzle of honey for added flavor and nutrition.
- Add oats to smoothies. Blending ¼ cup of rolled oats into your morning smoothie adds fiber and helps keep you full longer.
- Use oat flour in baking. Swap out some all-purpose flour for oat flour in muffins, pancakes or homemade bread.
- Try overnight oats. If you are short on time in the morning, prepare overnight oats the night before for a grab-and-go breakfast.
- Consider periodic high-oat days. Based on this study, eating several oat-based meals in a single day occasionally may offer a cholesterol-lowering boost—you could try an oaty fruit smoothie in the morning, then opt for savory oats, like our Sriracha, Egg & Avocado Overnight Oats, for lunch.
This study also highlights the importance of gut health for heart health. The phenolic compounds that helped lower cholesterol were largely produced by gut bacteria, so nurturing a healthy gut microbiome may amplify the benefits of eating oats. To support your gut bacteria, focus on eating a variety of fiber-rich foods and fermented foods like yogurt while limiting ultra-processed foods.
Our Expert Take
A new study published in Nature Communications found that eating oatmeal may help lower cholesterol levels, and the benefits appear to be driven in part by phenolic compounds that your gut bacteria produce when breaking down oats. A short-term, high-dose oat diet reduced LDL cholesterol by about 10% in people with metabolic syndrome, while a moderate daily oat intake helped maintain stable metabolic markers over six weeks. These findings add to the evidence that oatmeal is a heart-healthy food choice and suggest that your gut microbiome plays an important role in how your body benefits from oats. Adding oatmeal to your diet is an easy way to support your cardiovascular health.
